Robust Designs For MISO-Based Cognitive Radio Networks With Primary User´s Partial Channel State Information

Cognitive radio is an emerging technology improving the spectrum utilization efficiency in communication systems. In this paper, we are interested in a multiple-input single-output (MISO) based cognitive radio (CR) network where the secondary user (SU) shares the same frequency band with the primary user (PU). It is assumed that the SU transmitter (SU-Tx) has perfect channel information (CSI) from SU-Tx to SU receiver (SU-Rx), but partial CSI from SU-Tx to PU receiver. We propose a robust design method to determine the optimal transmission covariance of SU-Tx to maximize the rate of the SU while keeping the interference power to the PU less than a threshold with high probability. This problem is formulated as a semi-infinite programming (SIP) problem. Two algorithms are proposed to transform this SIP problem into a finite constraint problem, and it is shown that these algorithms obtain the optimal solution. Simulations are presented to validate the effectiveness of the proposed algorithms.